1. Field of the Invention
The present invention relates to focused ion beam tools and in particular to a system and method of permitting optical viewing and surface processing of semiconductor wafers and associated devices in parallel with ion beam processing of those wafers.
2. Description of Related Art
Focused ion beam (FIB) toots are widely used in processing of semiconductor wafers and associated devices (collectively referred to as electronic devices), particularly in circuit editing, failure analysis (FA) and mask repair applications. FIB tools have the ability to sputter away or deposit materials over selected microscopic areas. Though FIB tools are useful and powerful, they have limitations towards some applications. In circuit editing, for example, copper features are difficult to sputter cleanly with an ion beam, and new low dielectric constant (low-k) materials can be damaged by the FIB tool's gallium ion beam. In mask repair applications, the gallium ion beam can cause staining of the quartz mask substrate. It would be beneficial to have an alternative energy source to the use of a gallium ion beam in such instances.
FIB manufacturers, recognizing the benefits of optical viewing in a FIB tool, have incorporated microscopes into their tools. FEI Company of Hillsboro, Oreg. has incorporated an off-axis microscope in its VectraVision tools. However, the sample must be shuttled back and forth between the FIB and the optical microscope positions, so the user does not have the ability to perform real-time optical viewing during FIB processing. Additionally, the user cannot promote photo-chemistry at the surface. Credence Corporation of Milpitas, Calif. has incorporated an in-line microscope to an FIB, but it has a very large working distance and hence a relatively low resolution. Additionally, like the FEI tool, there is no possibility to use the microscope for optically-induced chemical modifications on the surface. It would be useful to be able to optically view the specimen surface during processing using FIB or other charged particle techniques such as scanning electron microscopy (SEM).